ggml : add ARM_NEON dequantize_row_q4_1()

ggml.c

@@ -1016,6 +1016,50 @@ static void dequantize_row_q4_1(const void * restrict vx, float * restrict y, in
             }
         }
     }
+#elif defined(__ARM_NEON)
+    for (int i = 0; i < nb; i++) {
+        const float32x4_t vd = vdupq_n_f32(x[i].d);
+        const float32x4_t vm = vdupq_n_f32(x[i].m);
+
+        const uint8_t * restrict pp = x[i].qs;
+
+        for (int l = 0; l < QK; l += 16) {
+            // Load 16x4-bit integers into 8x8-bit integers
+            const uint8x8_t v8 = vld1_u8(pp + l/2);
+
+            // Expand 4-bit qs to 8-bit bytes
+            const uint8x8_t v0 = vand_u8(v8, vdup_n_u8(0x0f));
+            const uint8x8_t v1 = vshr_n_u8(v8, 4);
+
+            // Interleave and combine
+            const uint8x8_t vx_0 = vzip1_u8(v0, v1);
+            const uint8x8_t vx_1 = vzip2_u8(v0, v1);
+
+            const uint8x16_t vq = vcombine_u8(vx_0, vx_1);
+
+            // convert to 2x uint16x8_t
+            const uint16x8_t vi_0 = vmovl_s8(vget_low_u8 (vq));
+            const uint16x8_t vi_1 = vmovl_s8(vget_high_u8(vq));
+
+            // convert to 4x float32x4_t
+            const float32x4_t vf_0 = vcvtq_f32_u32(vmovl_u16(vget_low_u16 (vi_0)));
+            const float32x4_t vf_1 = vcvtq_f32_u32(vmovl_u16(vget_high_u16(vi_0)));
+            const float32x4_t vf_2 = vcvtq_f32_u32(vmovl_u16(vget_low_u16 (vi_1)));
+            const float32x4_t vf_3 = vcvtq_f32_u32(vmovl_u16(vget_high_u16(vi_1)));
+
+            // multiply by d and add m
+            const float32x4_t r0 = vmlaq_f32(vm, vf_0, vd);
+            const float32x4_t r1 = vmlaq_f32(vm, vf_1, vd);
+            const float32x4_t r2 = vmlaq_f32(vm, vf_2, vd);
+            const float32x4_t r3 = vmlaq_f32(vm, vf_3, vd);
+
+            // Store
+            vst1q_f32(y + i*QK + l +  0, r0);
+            vst1q_f32(y + i*QK + l +  4, r1);
+            vst1q_f32(y + i*QK + l +  8, r2);
+            vst1q_f32(y + i*QK + l + 12, r3);
+        }
+    }
 #else
     for (int i = 0; i < nb; i++) {
         const float d = x[i].d;